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Organic Reaction Intermediates and Mechanisms

In an Organic Reaction Mechanism, a Reaction Intermediate is a molecular entity that is formed by the reactants which reacts further to form the products. Although, there are a multitude of organic reactions with multiple mechanisms and intermediates, there are a few reaction mechanisms which form the foundations of organic reactions. One of these is the Nucleophilic Substitution Reaction which involves an electron nucleophile attacking a positively charged atom (which is usually a carbon) in order to substitute a leaving group. These reactions can be broken down into two further categories: SN1 and SN2.

SN1 reactions are substitution reactions where the rate-determining step is unimolecular. This suggests that the mechanism is only dependent on the electrophile, and totally independent of the nucleophile. Knowing these details, it can be inferred that the intermediate that forms in the reaction, if the electrophile is carbon-based, is a carbocation.  After the carbocation forms, then the nucleophile will subsequently attack it based on the opposition of charge. Thus the leaving group was replaced by a nucleophile – hence the term SN1 (unimolecular nucleophilic substitution reaction).

SN2 reactions are also substitution reaction, but with a different reaction mechanism, as it proceeds in a bimolecular manner. The nucleophile in this case attacks the electrophile without a leaving group leaving. Thus, a temporary transition state with five substituents around the carbon is formed. Eventually, the leaving group leaves and the structure around the central carbon inverses.

Although nucleophilic substitution reactions are prevalent in Organic Chemistry, there are other important reactions such as Elimination Reactions, which may share some of the reaction mechanisms and intermediates, such as the carbocations. Thus, in Organic Chemistry, it is most often the physical and chemical conditions which determine which intermediates form as well as the direction of a particular reaction.

TLC Analysis of Midol

A student obtained a silica gel TLC plat shown in attached figure by spotting samples of Midol, caffeine and acetaminophen on the plate, then eluting with petroleum ether: chloroform What are the Rf-values of acetaminophen and caffeine, respectively? Based on this TLC analysis, what are the ingredients in a tablet of Midol? W

Chromatography: Benzoic Acid and Aniline

1. Benzoic acid is soluble in diethyl ether but not water; however, benzoic acid is extracted from diethyl ether with aqueous sodium hydroxide. Complete the acid-base reaction below by writing the products of the reaction and label the acid, the base, the conjugate acid and the conjugate base. The diagram attached below.

The Order of Elution in Column Chromatography

In normal phase column chromatography, which solvent has more eluting power: petroleum ether or dicloromethane? In what way is the eluting power of a solvent related to its polarity? In normal phase column chromatography, how does the principle of like dissolve like explain the affinity of a compound for the mobile phase, relati

TLC Plates: Developing Chambers and Solvents

Why should a TLC plate be removed before the solvent before the solvent front reaches the top of the plate? Why should the developing chamber for a TLC plate not be open to the atmosphere? For each TLC plate in the diagrams attached, state whether the spotting method was correct or incorrect, and why?

Chemistry

Naphtalene is soluble in diethyl ether, but it is insoluble in water regardless of the solution pH. Explain why this compound cannot be readily ionized in aqueous solution. There are three common functional group in organic chemistry that are readily ionized by adjusting the pH of the aqueous solution during an extraction. Na

Reactions of Carbonyl Compounds

See attachment for better symbol and reaction representation. 1. Complete the following reaction by drawing a structural formula for the product. ? • You do not have to consider stereochemistry. • You do not have to explicitly draw H atoms. 2. Draw a structural formula for the major organic anion formed when

t-butyl chloride to t-butanol mechanism

t-butyl chloride (Compound A) generates either tert-butanol (Compound B) or 2-methyl-1-propene (Compound C) in the presence of water as shown below: Please see attachment for diagram. (a) Product B is the result of what type of reaction? Circle one. Sn1 Sn2 E1 E2 (b) Product C is the result of what type of

Biologically important reactions

The structures of the active sites of three copper containing metalloenzymes (A, B, and C) are shown below together with three biologically important reactions (I, II, and III). [His = Histidine] For each reaction, identify the active site that catalyses the conversion and, with the aid of diagrams, describe the mechanisms i

Separating Catenated Circular DNA Complexes

Two circular DNA duplexes are catenated, or captured as interlocking rings. Draw a general mechanism that shows how these could be resolved into two free circles. You don't need to draw individual base pairs or a precise chemical mechanism of esterification by an active site tyrosine, but you do need to demonstrate generally how

Organic Halogen Compounds

I am requesting help with the following questions. If possible please format in a Word Document: 1. Tell what products you expect and by what mechanism they are formed for each of the following reactions: a. 2-chlorohexane + ethanol b. 2-chlorohexane + sodium ethoxide (in ethanol) c. 2-chlorohexane + sodium hydrosulfi

Structures and Natural Products

See the attached file. 11. Refer to Exhibit 9-7. Two structures have been proposed for this natural product. Circle the structure that is consistent with the information presented and briefly explain your choice. 12. Draw a structure for a singly substituted chiral chloroalkane that contains four carbon atoms with R stere

Organic Halogen Compounds

Select an alkyl halide and a nucleophile that will give each of the following products: Please refer to the attachment for full questions.

Elimination and Substitution

Your given a cyclohexane ring with a dashed Chlorine at C1 and a wedged methyl at C1, also there is wedged methyl at C2 and C6. Thus making there no trans protons available on these carbons for elimination (except methyl connected to chiral carbon w/chlorine, I think) the questions requires you to determine Substitution products

Reaction Mechanism for Enantiomerically Pure (S)-2-Iodobutane

Enantiomerically pure (S)-2-Iodobutane is reacted with sodium iodide in acetone. The measured optical rotation of samples taken from the reaction mixture changes from an initial maximum value of +16 degrees, to 0 degrees over time. If the reaction is performed with isotopically labeled iodine it is found that the rate of decreas

Oraganic Chemistry: Reaction Mechanisms

* What would happen to the rate of Sn2 reaction if the solvent was changed from acetone to water? * How do E1 and E2 mechanisms depend on the properties of a base? * What is the difference between polar protic solvent and polar aprotic solvents and how do they determine if a reaction is going to be sn1, sn2,E1 or E2

2-Bromopropane and Ethoxide Ion

When 2-bromopropane reacts with ethoxide ion, two products are formed; one is the product of Sn2 substitution and the other is the product of E2 elimination. Write the structure of both products, and tell how they could be distinguished using IR spectroscopy.

Reaction of bromomethane with sodium hydroxide

Would you please help me understand the following question: Reaction of bromomethane with sodium hydroxide in water forms methanol. If soldium iodide is added to the reaction mixture, the rate of methanol formation is dramatically increased (i.e. sodium iodide is a catalyst). The mechanism involved in the reaction of CH3B

If you look at a reaction for an esterification reaction, you cannot tell where the oxygen comes from (acid or alcohol). Draw the mechanism of this reaction, and devise an experiment using the mechanism and O18 (O18 isotope) to help prove unequivocally where the oxygen comes from.

1. If you look at a reaction for an esterification reaction, you cannot tell where the oxygen comes from (acid or alcohol). Draw the mechanism of this reaction, and devise an experiment using the mechanism and O18 (O18 isotope) to help prove unequivocally where the oxygen comes from. 2. The Fischer Esterification is highly r

Drawing Compounds, Alkyne and Alkyl Bromide

1.) Draw the two compounds (one containing N and the other Br) that could react by SN2 reaction to give the following compound: (see image attached). 2.) Draw the simpler alkyne and alkyl bromide that could be combined to give the alkyne shown: (see image attached).

Describe the mechanism of aromatic substitution in anisole

Write down the mechanism of nitration of anisole along with the sigma complex intermediate for ortho, meta, para nitration. By using sulfuric acid with nitric acid to form the nitronium ion electrophile derive the mechanism of reaction. Please answer attached. thanks

Reactants as Electrophiles and Nucleophiles

1) Label the reactants as electrophiles or nucleophiles. Use curved arrows to show the movement of electron pairs in the reactions: (a) methoxide + methyl chloride = dimethyl ether + chloride (b) (CH3)3O+ + HOH = CH3OCH3 + CH3OH2+ 2) For the pair of compounds, dipropylamine and triethylamine, circle the compound you e

Sn2 Reactions

Arrange the following compounds in order of increasing reactivity in an Sn2 reaction. First present the structure of the compounds and then rank them with clear explanations. bromocyclohexane; 1-bromo-1-methylcyclohexane; 1-bromomethylcyclohexane; (1-bromoethyl)cyclohexane; and 1-bromo-2-cyclohexylethane

DDT and its Effect on Peregrine Falcon Eggshells

The banned pesticide DDT has been identified as the cause of thin egg shells produced by Peregrine falcons. What chemical process did DDT disrupt? Explain your answer. Response needs to be in 200-300 word essay form.

Aldol Addition Reaction Mechanism

Which one of the following best represents the flow of electrons in the key step for the aldol addition reaction that occurs when propanal is treated with sodium hydroxide?

Sodium Borohydride Reduction of Aldehydes to Alcohols

Draw the isomeric pentanols (C5H12O) that can be synthesized via a sodium borohydride reduction of an aldehyde. In your experiment you use ligroin in a trituration. a. What could be used besides ligroin. b. What is chemically occurring when you use the ligroin? The experiment was a Grignard experiment. I am having a hard

Ester synthesis and reaction problems

Please see the attached file. 1. Consider the reaction sequence below to answer the following questions: Compound X, diethyl propanedioate, is more commonly known as_____. 2. Consider the reaction sequence below to answer the following questions: The starting material A in this reaction sequence is called a __

Organic Chemistry Reactions: Example Problems

Please see attached file for the properly formatted question. A reaction of a tertiary alkyl halide gives two products. Where do they come from (SN1, SN2, E1 or E2) processes? What are the mechanisms for these processes?

Which SN1 reaction is faster?

Which reaction is faster and what is the kinetics of these reactions? a) (CH3)3CCl ----> (CH3)3COH (in 70% water/methanol) b) (CH3)3CCl ----> (CH3)3COH (in 50% water/acetone) The faster reaction is shown and the kinetics are discussed.